Recent developments on the admissibility of patent term extension in Japan

Drugs are not allowed to be marketed without a marketing authorization. Taking into account the investment on R&D for a new drug and the necessity to recoup such investment, the patent term may be extended by a period not exceeding 5 years if there is a period during which the patented invention cannot be worked. Later in this post, I will discuss the judgment of the Japanese Supreme Court in 2015, which caused the guidelines on patent term extension to be significantly amended.


Since the scope of a patented invention is determined abstractly, it is not rare that more than one marketing authorization is obtained for one patented invention. For example, with regard to a patented invention regarding an effective component for nasal inflammation, the second authorization for a micro-capsule-type drug could be obtained, even after the first authorization for nasal-spray-type drug has been obtained. For a long time, it has been a big issue whether or not the patent term may be extended more than once (i.e., by every single marketing authorization).

Under the previous practice of the Japan Patent Office (JPO), term extension was admitted only once for one patent. The JPO rejected the second application for extension, if the second authorization was sought for a drug with the same effective component, efficacy and result. As for the above-mentioned example, the application for extension on the second authorization (micro-capsule-type drug) would be rejected despite the fact that a patentee is unable to work the micro-capsule-type drug during the time when no market authorization has yet been approved for this drug.

In 2015, the Supreme Court took a different stance and changed the previous practice, establishing new standard for the examination of an extension. It held that even if the second drug has the same effective component, efficacy and result, the second application regarding the second authorization should not be rejected if the second authorization has any difference in quantity, usage, dosage. The only exception for rejection of the second application is in a case where the second authorization is comprehended in the first authorization in terms of component, quantity, usage, dosage, efficacy and result.


Why did the Supreme Court take into account additional factors; quantity, usage and dosage? Some authorities analyze it is due to a recent change in the mainstream of drug development. More R&D has been recently focused on “Drug Delivery Systems” which are engineered technologies for necessary effective components to be properly delivered to the targeted diseased parts for necessary period of time. For these technologies, drug researchers put more energy to find the best drug form, quantity, usage and dosage rather than to find new effective component, efficacy and result. The Supreme Court’s judgment is in line with this recent change, making the patent term extension system more realistic than in the previous practice.


Hirotaka Nonaka

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